The Primary Modular Tibia: Regardless of Age & BMI

So, if you want to eliminate poly wear, a one-piece implant will do that for you.

So, I would propose using modularity when you need it, but not always. And I’d say in two-thirds of our cases we can use a one-piece implant.

These are the 3 general conditions when I use modularity:

1. The first is if you want to change the articular congruity with an anterior stabilized or “dished” or ultra-congruent implant. I think it’s an excellent option if your flexion laxity is a little bit greater than your extension, then you don’t want to mess with the bone cuts, you can add an ultra-congruent type device. If you want to get into 1mm increments for balancing the gaps, I think we use modularity in those cases with the 11 or 13 implants. If you want to use a PS or perhaps you have iatrogenic imperfecta and you might need the little bit more stabilization of a PS+ type implant, we’ll use modularity.
2. And then as Aaron pointed out, stems, augments are sort of the rare primary case where you need something else.
3. Or perhaps in the very young, we still use one-piece implants, but if you want some other type of polyethylene option, modularity works.

Our premise is: we use one-piece implants with modular capabilities. And I would say, “What are the results of this workflow?”  So, we’ve done this for a number of years.

We looked at a 10-year period. We’d done roughly 10,000 knee arthroplasties of all flavors. The indications for selecting one-piece versus modular implants were based on the surgeon’s selection. We found a sub-cohort of 2,000 knees with the same articulation, with two different designs. One was modular and one was a one-piece that had the ability to remove the polyethylene later if need be. Roughly half of them were the one-piece implant. It’s a cemented cobalt-chromium tray, standard demographics for almost all series.

If you look at reoperation for the modular prosthesis, 0.6% required a reoperation at mid-term follow-up. Two of these were for infection; 4 were aseptic (Kaplan Meier Survivorship; p=0.76. Wilcoxon test). There was no difference in survivorship between the one-piece implants at early follow-up compared to the non-modular implants.